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Wrap-Around Dune
▶Climbing Dune
Wrench Fault
▶ Strike-Slip Faults
Wrinkle Ridge
Jarmo Korteniemi1,2, Lisa S. Walsh3 and
Scott S. Hughes4
1Earth and Space Physics, Department of
Physics, University of Oulu, Oulu, Finland
2Arctic Planetary Science Institute, Rovaniemi,
Finland
3Center for Earth and Planetary Studies, National
Air and Space Museum, Smithsonian Institution,
Washington, DC, USA
4Department of Geosciences, Idaho State
University, Pocatello, ID, USA
Definition
Asymmetrical ridge, typically composed of
a broad linear rise and complex crenulations,
which occur on a broad, low-relief arch
(Watters 1988; Schultz 2000).
Synonyms
Descriptive: ridge, mare ridge, wrinkled mare
ridge, mare ridge-highland scarp system
(Lucchitta 1976). Interpretative: contractional
lineament, Bergader (‘mountain vein’, german,
Schro¨ter 1791), pressure ridge
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Description
Linear arc-shaped or sinuous topographic highs,
preferentially found on lowland/plains areas
(Golombek et al. 2001), occurring in quasi-
regular or periodic spacing (Watters 1991) often
in en echelon overlapping sets. They are often
bifurcating or anastomosing (Lucchitta and
Klockenbrink 1979), braid, and rejoin along
strike (Plescia and Golombek 1986). They have
asymmetrical profiles (one side having a steeper
slope than the other).
Morphometry
Wrinkle ridges are 10s–100s of m high (highest
on Mercury), up to 100s of km long, and few to
10s of km wide, displaying 10s of km spacing.
Mercury (in the northern smooth plains and in
and around Caloris Basin): Wrinkle ridges are

112–961 m high (mean = 187 m) and

10–241 km long (mean = 53 km) (Walsh
et al. 2013).
Venus (Fig. 1): Wrinkle ridges are 1–5 km
wide, 100s of m high, and 100s of km long.
They often form large-scale parallel sets with
interridge spacing of few tens of km. These wrin-
kle ridge sets extend for 1,000s of km (Bilotti and
Wrinkle Ridge,
Fig. 1 Venus: subparallel
wrinkle ridges, some
displaying smaller-scale
lineation, in Aditi Dorsa
near 31S 194E. Magellan
left-look radar (NASA/
JPL)
Wrinkle Ridge, Fig. 2 Serpentine Ridge (Dorsa
Smirnov) in Mare Serenitatis on the Moon, concentric to
the mare basin, centered 28N 30E. LROC
M117338863M and M117318506M (NASA/GSFC/ASU)
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Suppe 1999). On Venus, they are systematically
narrower and have shorter spacing than on other
terrestrial planets (Kreslavsky and Basilevsky
1998).
Moon (in mare basins and several craters)
(Figs. 2 and 3): Wrinkle ridges are 
33–590 m
high (mean = 187 m) and 
10–241 km long
(mean = 53 km) (Walsh et al. 2013).
Mars (Figs. 4 and 5): Wrinkle ridges are
10–20 km wide, 10s–100s of km long, and
80–250m high (in Solis Dorsa, Fig. 4), showing
elevation offsets of the plains on either sides of
Wrinkle Ridge,
Fig. 3 Moon: perspective
view of wrinkle ridges near
Mons La Hire, in Mare
Imbrium. AS15-M-1555
(NASA/JPL/ASU)
Wrinkle Ridge,
Fig. 4 Solis Dorsa:
subparallel wrinkle ridges
in Solis Planum, Mars.
MOC mosaic (NASA/JPL/
MSSS)
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wrinkle ridges ranging 50–180 m (Golombek
et al. 2001). Tharsis wrinkle ridges have an aver-
age spacing of 30–50 km (Watters 1991; Head
et al. 2002).
Subtypes
Based on orientation (Bilotti and Suppe 1999;
Head et al. 2002):
(1) Unimodal/subparallel (Figs. 1 and 4)
(2) Bimodal (with two equal trends or a major
and a minor trend) (Fig. 5)
(2.1) Orthogonal
(2.2) Oblique
(3) Polygonal (parallel trends interrupted by var-
iable angular orientations)
(4) Random
(5) Ring (▶wrinkle ridge rings)
Formation
Wrinkle ridges are contractional tectonic features
formed by a combination of folding and thrust
faulting. They form in response to uniformly
distributed compressional stresses in the upper
layers of the surface where a strong brittle layer
overlies a weaker layer (e.g., lava overlying
megaregolith or layering present in lava flows).
They accommodate very low amounts of short-
ening strain (Mueller and Golombek 2004).
Their formation is not consistent with a medium
where a weak layer overlies another weak layer
(e.g., sediment overlying megaregolith) (Head
et al. 2002; Mueller and Golombek 2004).
Compressional stresses may be induced by
lithospheric loading of volcanic plains (e.g.,
mare basalts (Watters 1993)), sediments, lahar-
like deposits, water, or ice (Thomson and Head
2001).
Wrinkle Ridge, Fig. 5 The Hesperia Dorsa wrinkle
ridges that show bimodal trending in Hesperia Planum,
Mars, (a) THEMIS IR mosaic centered 20S 113E
(NASA/JLP/ASU), (b) CTX: B01_010152_1606_XN_
19S245W (NASA/JPL/MSSS)
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Formation Models
(1) Simple thrust fault in rigid crustal blocks
(Schultz 2000 and references therein).
(2) Conjugate thrust fault (pop-up model):
a wrinkle ridge is a wedge bounded by two
conjugate thrust faults (Schultz 2000 and ref-
erences therein).
(3) Thrust faults and backthrust fault: thrust
faulting causes the main ridge, whereas wrin-
kles are interpreted as backthrust faults
(Schultz 2000).
(4) Low-amplitude compressive anticlines
above subsurface blind thrust faults: anticli-
nal folding of rocks occurs over a buried
(blind) thrust fault. Wrinkle ridges form as
the subjacent fault propagates upward
(Plescia and Golombek 1986; Bilotti and
Suppe 1999 and references therein,
Golombek et al. 2001).
(5) Low-amplitude buckle fold: “folds, resulting
from buckling followed by reverse to thrust
faulting (flexure-fracture).” In this model,
wrinkle ridges are shallow near surface struc-
tures (Watters 1991 and references therein,
Schultz 2000 and references therein).
Possible Sources of Compressive
Stresses
These include (1) thermal subsidence following
plume-related thermal topographic uplift, (2) sub-
sidence in response to volcanic surface loading
by flood basalts, (3) subsidence due to deep
crustal loading by dense underplated magmas
(Me`ge and Ernst 2001), and (4) global contrac-
tion due to interior cooling. Global contraction
may have a more substantial contribution to wrin-
kle ridge formation onMercury than on theMoon
(Walsh et al. 2013; Byrne et al. 2014). On Venus,
wrinkle ridges are estimated to represent little
(
2–5 %) regional shortening of the terrain
(Bilotti and Suppe 1999). Global distribution on
Mars is proposed to be associated with
a hypothesized global contraction (Nahm and
Schultz 2011).
Controls
On Mercury, they are longer and higher than on
the Moon, which may be due to differences in
thickness of plains material that controls the max-
imum depth of faulting, contribution of subsi-
dence, and amount of global contraction (Walsh
et al. 2013).
Age
Interaction of wrinkle ridges with craters onMars
(Allemand and Thomas 1995; Mangold
et al. 1998; Head et al. 2002) indicates that wrin-
kle ridges formed significantly later than the plain
units they deform. However, their formation has
apparently ceased long ago.
Surface Units
Wrinkle ridges may display one, or several of the
following (Strom 1972; Lucchitta 1976; Fig. 3):
(1) Broad arch: a broad, low-relief arch on which
wrinkle ridges develop. “A linear to convex
slope that rises from a flat or slightly tilted
surface toward the center of the ridge”
(Mueller and Golombek 2004). Most authors
make this arch a part of a wrinkle ridge struc-
ture, but Schultz (2000) notes that they may
or may not be genetically related to wrinkle
ridges and they may be only spatially associ-
ated. On Mars, Solis Planum, they are about
50 m high and 30–50 km wide (Mueller and
Golombek 2004).
(2) Ridge: broad, linear rise, or ridge or hill. It is
generally narrower and steeper than the broad
arch (Mueller and Golombek 2004).
(3) Wrinkle: sinuous, complex, narrow,
low-relief, discontinuous, or en echelon cren-
ulations (the wrinkles) typically near
a ridge’s margin, sometimes on its top or in
the surrounding terrain (Schultz 2000).
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Composition
They are consistently located in stratified volca-
nic and sedimentary deposits (Mueller and
Golombek 2004). Based on stratigraphic rela-
tions, wrinkle ridges may deform the following
material units:
(1) Volcanic plains.
(2) Sedimentary plains.
(2.1) Mantled wrinkle ridge (Thomson and
Head 2001) deposition of sediment was
subsequent to wrinkle ridge formation.
(2.2) Wrinkle ridge formed in the sedimen-
tary layer.
(3) Impact ejecta plains.
Prominent Examples
On Venus, Aditi Dorsa (Fig. 1); on the Moon,
Dorsa Smirnov and Dorsa Lister (Serpentine
Ridge) wrinkle ridge system in Mare Serenitatis
(Fig. 2).
Distribution
Wrinkle ridges occur on topographically smooth
material on the Moon, Mercury, Mars, and Venus
in two physiographic settings: the interior of large
impact basins (e.g., Mare Serenitatis on theMoon
or the Caloris Basin on Mercury) and on broad
expansive plains (e.g., the northern plains ofMer-
cury) (Watters 1988; Watters and Johnston 2010;
Watters and Nimmo 2010).
On Mercury, they occur in the smooth plains
and the Caloris Basin interior and exterior
(knobby/hummocky) plains (Plescia and
Golombek 1986 and references therein, Watters
et al. 2009; Walsh et al. 2013).
On Venus, they mostly occur in the ▶wrinkle
ridge (regional) plains unit. Majority of plains
with wrinkle ridges lie below the mean planetary
radius (in geoid lows). Aditi Dorsa shows the
highest density of wrinkle ridges (Bilotti and
Suppe 1999).
On the Moon, wrinkle ridges are found in the
mare basins (Masursky et al. 1978; Plescia and
Golombek 1986) (see figure in ▶ linear rille) and
in craters (e.g., Vitello, Kugler, Karrer, and
Grimaldi) (Walsh et al. 2013).
On Mars, they are distributed globally
(Chicarro et al. 1985; Nahm and Schultz 2011)
and mostly occur in the Hesperian ▶Wrinkle
ridge plains (Head et al. 2002). Wrinkle ridges
show a circumferential trend around Tharsis
(e.g., Nahm and Schultz 2011). Martian wrinkle
ridges are up to 400–600 km long, and yet they
seem to accommodate very low local strains
(about 100s of m of shortening across individual
ridges) (Mueller and Golombek 2004).
Significance
They are the result of horizontal shortening of the
surface strata (Schultz 2000). Wrinkle ridges are
generally thought to indicate volcanic layers,
partly because volcanic features are of greater
abundance on planetary surfaces. However, wrin-
kle ridges per se are only indicative of a stack of
subsurface layers or vertical inhomogeneity in
the material (Gregg and de Silva 2009 and refer-
ences therein).
Terrestrial Analog
The best analogs are found in the anticlinal ridges
of the Yakima fold and thrust belt of the Colum-
bia River Plateau in the Pacific Northwest,
interpreted as layered basalt flows draped over
thrust faults (Lucchitta and Klockenbrink 1979;
Plescia and Golombek 1986; Watters 1988);
small foreland basement uplifts (e.g., Oregon
Basin thrust, Wyoming, USA) (Golombek
et al. 2001) produced by anticlinal folding of
rocks above reverse faults that become shallow
and typically break the surface (Plescia and
Golombek 1986). Some of the terrestrial analogs
formed in a layered sedimentary material (e.g.,
Meckering, Australia; El Asnam, Algeria)
(Plescia and Golombek 1986).
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History of Investigation
Originally found to exist on lunar maria by tele-
scopic observations, wrinkle ridges were named
Bergader (German, mountain + vein) by
Schro¨ter (1791:}335, 356); he described other
similar types as “light veins” (Lichtadern) or
gray veins that were only visible near the termi-
nator. Schro¨ter first observed and described the
“snake-like” wrinkle ridge (Fig. 6) later called
Great Serpentine Ridge in English (Elger 1895)
(today: Dorsa Smirnov). Beer and M€adler
(1837:126}70) also noted that these low ridges
can be seen only near the terminator.
J. Phillips “compared the lunar ridges to long,
low, undulating mounds, of somewhat doubtful
origin, called ‘kames’ in Scotland, and ‘eskers’ in
Ireland,” while others suggested that they “repre-
sent old submarine banks formed by tidal cur-
rents, like harbour bars, or glacial deposits; in
either case, to be either directly or indirectly due
to alluvial action” (Elger 1895).
Kuiper (1954) suggested that wrinkle ridges
result from compression due to downward-
moving differential cooling of the crust: when
“cooling in the outer shell had largely run its
course, and gradually deeper and deeper layers
followed. This caused the deeper layers to shrink
in turn; but now the outer layers, in which the
cracks had meanwhile been largely filled by new
lavas, began to be compressed, since their tem-
peratures were nearly constant but their base
narrowed. Folding would therefore result. In this
manner the ridges, visible particularly on the
maria, may be explained” (Kuiper 1954).
Most models in the 1960s focused on volcanic
intrusion or extrusion, controlled by global or
basin-related tectonic patterns (Lucchitta 1976
and references therein).
In the 1970s, an alternative model to explain
thrust faulting was the model of regional cooling
of volcanic plains, which was subsequently
rejected (Mangold et al. 2000).
Schultz (2000) called wrinkle ridges “proba-
bly one of the most commonly observed, yet least
understood, classes of planetary structures.”
Database
Bilotti and Suppe (1999) mapped over 65,000
wrinkle ridges on Venus.
IAU Descriptor Term
▶Dorsum, dorsa (e.g., in lunar maria).
Similar Landforms
▶High-relief ridge;▶ lobate scarps: smaller than
wrinkle ridges and usually found in the highlands
but also in mare materials and in transition to
wrinkle ridges (Lucchitta and Klockenbrink
1979; Watters 1993; Head et al. 2002; Watters
et al. 2010).
Wrinkle Ridge, Fig. 6 First depiction of the Serpentine
Ridge on the Moon (see Fig. 2) (Table 10 from Schro¨ter
1791) (e-rara.ch)
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See Also
▶Reverse Fault
▶Wrinkle Ridge Plains
▶Wrinkle Ridge Ring
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Wrinkle Ridge Plains
Scott S. Hughes
Department of Geosciences, Idaho State
University, Pocatello, ID, USA
Definition
Plain that has developed topographically distinct
sinuous or nearly linear ridges on an otherwise
relatively smooth surface.
Category
A type of ▶ volcanic plain.
Synonyms
Dorsum plains; Plains with wrinkle ridges
(Moon, Venus); Regional plains (Venus); Ridged
plains (Mars); Wrinkle ridged plains (Mars)
Description
Wrinkle ridge plains (e.g., Watters 1991) are
characterized by two principle topographic fea-
tures: broad ridges up to tens of kilometers wide
and sinuous and discontinuous (or en echelon)
crenulations on or near ridges (Schultz 2000).
Morphometry
▶Wrinkle ridge
Interpretation
Contractional tectonic features on volcanic or
sedimentary plains (e.g., Watters 1993). On the
Moon, formed by contraction related to subsi-
dence of lava flow sequences in lunar maria
(basins); on the high volcanic plains of Mars,
Venus, and Mercury, related more to internal
tectonic forces caused either by gravitational
loading of large volcanic constructs or by coupled
mantle-crust dynamics including mantle plumes.
The relatively linear ridges on the wrinkle ridge
plains of Mars have distinct elevation offsets and
are interpreted to represent subsurface thrust
faults (Golombek et al. 2001). Me`ge and Ernst
(2001) interpret wrinkle ridges on Earth, Mars,
and Venus as contractional structures (thrust-
faulted anticlines) related to mantle plumes.
Formation
After emplacement, plains material is subse-
quently deformed by compressional/contrac-
tional forces producing ▶wrinkle ridges
(Basilevsky and Head 1996). Wrinkle ridge
plains on lunar mare basins, developed by thin-
skinned buckling during cooling, contraction,
and subsidence of basin interiors, are likely
caused by loading of multiple layers of lava
(several kilometers thick in basin interiors) that
resulted in compressional tectonic forces and
shortening of surface layers. The wrinkle ridge
plains on high-elevation plains of Mars are devel-
oped by thick-skinned compressional tectonic
forces in the lithosphere leading to deep-seated
thrust faults (Golombek et al. 2001; Monte´si and
Zuber 2003), whereas wrinkle ridge plains
(regional plains) on Venus are interpreted to
reflect tectonic deformation related to mantle
convection motions coupled to a more rigid
crust (Squyres et al. 1992).
Age
On Venus, wrinkle ridges are abundant on volca-
nic plains that represent an extensive episode of
2364 Wrinkle Ridge Plains